Although intraspecific trait variability (ITV) is known to decrease with the increasing spatial extent, few studies have addressed how it behaves accross different ecological scales alongside short environmental gradients and which factors drive this variation. We verify whether functional traits of a characteristic species of riverine forests exhibit greater inter- (regional scale) than intra-population (local scale) ITV and whether environmental factors are affecting its functional traits. We sampled four populations of Gymnanthes klotzschiana from different geomorphological regions in southern Brazil and collected data of leaf area (LA), leaf dry matter content (LDMC) and total height from seven adult individuals per plot. We observed significant differences among populations and greater variability at the inter- than intra-population scale for LDMC and total height. Leaf area exhibited greater intra-population variation. Cation exchange capacity and available phosphorus affected positively LDMC. Base saturation influenced negatively total height. Difference between mean canopy height and mean height of G. klotzschiana exerted negative effects on LDMC and total height and positive effetcs on LA. Our results demonstrate LDMC and total height to be suitable functional traits for studies on ITV at the regional scale and reinforce the need of considering it in ecological studies, including on a regional scale.

尽管已知种内性状变异性（ITV）随着空间范围的增加而减小，但很少有研究涉及它在不同的生态规模以及短的环境梯度下的行为，以及驱动这种变化的因素。我们验证了河系森林特征物种的功能性状是否表现出比种群内（局部规模）ITV更大的区域间（区域尺度），以及环境因素是否正在影响其功能性状。我们抽样了四类裸Gym草（Gymnanthes klotzschiana）来自巴西南部不同地貌区域的数据，并从每个样地收集了七个成年个体的叶面积（LA），叶干物质含量（LDMC）和总高度的数据。我们观察到人群之间的显着差异，并且LDMC和总高度的种群间比种群内规模更大。叶面积表现出更大的种群内变异。阳离子交换能力和有效磷对LDMC有积极影响。基础饱和度对总高度产生负面影响。G. klotzschiana的平均冠层高度与平均高度之间的差异对LDMC和总高度产生负面影响，对LA产生正面影响。我们的结果表明，LDMC和总高度是适合在区域范围内进行ITV研究的功能性状，并加强了在生态研究中（包括区域范围内）对其进行考虑的需求。